1. Field of the Invention
The invention relates to a liquid crystal display, and in particular, to a liquid crystal display circuit design.
2. Description of the Related Art
FIG. 1 shows a conventional display panel. The display panel comprises a timing controller (TCON) 102 for receiving differential signals like LVDS/TMDS/DVI, and two buses each coupled to a plurality of source drivers 104. For example, all of the odd source drivers 104 may couple to the one bus, while all the even source drivers 104 may couple to the other bus. Given a 6-bits gray level, a total of 18 transmission lines is required to deliver red, blue and green information from the TCON 102 to each source driver 104. Thus two buses utilize 36 transmission lines in total. If the gray level is 8 bits, 48 transmission lines are required. After the TCON 102 receives the LVDS/TMDS/DVI signals, the corresponding image information is transmitted to the source drivers 104 via the transmission lines. Signals on the transmission lines electrically conform to the TTL logic standard, and have a voltage of 3.3 V or 5V. The display panel also comprises a reference voltage generator 106, providing voltages based on gamma correction parameters.
FIG. 2 shows a conventional advanced display panel. The TCON 202 comprises a bus, both ends of which are equipped with terminators 208. All source drivers 204 simultaneously couple to the bus, thus the number of required transmission lines is reduced by half that of FIG. 1. Given a 6-bits gray level, the TCON 202 only requires 18 transmission lines to couple all source drivers 204. After the TCON 202 receives the LVDS/TMDS/DVI signals, image information is delivered to the source drivers 204 via the transmission lines, and signals on the transmission lines electrically conform to the reduced swing differential signal standard (RSDS). Similarly, the display panel also comprises a reference voltage generator 206, providing voltages based on gamma correction parameters.
FIG. 3 shows a conventional point-to-point display panel. The TCON 302 connects to each source driver 304 with individual transmission lines, and signals on the transmission lines conform to the point-to-point differential signal (PPDS) standard. The transmission lines are exclusive for each individual source driver 304, therefore the bus clock need not be shared, and the transmission rate can be significantly increased. Moreover, only a few transmission lines are required to deliver red, green, blue, and additional data. Similarly, the display panel also comprises a reference voltage generator 306, providing voltages based on gamma correction parameters.
Although PPDS reduces the number of transmission lines and the cost of PCBs, additional DC biased current is still required, thus, the power provided is inadequate for portable products. Additionally, with the progress of current technology, logic voltage requirement have been reduced from 5V to 1.8V/1.5V, making the implementation of differential signal will be more difficult.